Lecture 5.2: Viral Adaptations Flashcards
(28 cards)
Viral Cell Cycle
• Attach
• Enter
• Replicate
• Exit
An Overview of the Spanish Flu
• The 1918 influenza
• H1N1 virus with genes of avian origin
• About 500 million people or 1/3 of the world’s population was infected
• 50 million deaths worldwide
What is the Influenza Virus?
• Is an orthomyxovirus
• Virions are surrounded by an envelope
• Genome is single-stranded RNA
• Allows a high rate of mutation
What is a Serotype?
A variation within a microbial species, distinguished by the humoral immune response
What are the main serotypes of Influenza Virus?
• A, B, and C
• Differences are based on antigens associated with the nucleoprotein
What can Influenza A infect?
• Avian Hosts
• Mammalian Hosts
What can Influenza B infect?
• Humans only
Major influenza A subtypes that have infected humans during seasonal epidemics (3)
• H1N1
• H2N2
• H3N2
What are the surface glycoproteins of Influenza A? (2)
• Hemagglutinin (HA)
• Neuraminidase (NA)
Structure of the Influenza Virion
• Hemagglutinin (HA)
• Neuraminidase (NA)
• Lipid Envelope
• Protein Envelope
• M1 & M2
• RNA
Signs and Symptoms of Influenza
• Sudden fever
• Pharyngitis
• Congestion
• Cough
• Myalgia
Basic Treatments for Influenza
• Symptomatic care
• Anticipation of potential complications
Best Treatments for Influenza
• Rest and fluid intake
• Conservative use of analgesics for myalgia and headache
• Cough suppressants
Antiviral Medications (4)
• Amantidine
• Rimantadine
• Oseltamivir
• Zanamivir
What are the 2 main processes by which mutations occur?
• Antigenic Drift
• Antigenic Shift
What is Antigenic Drift?
Involves the accumulation of a series of minor genetic mutations
What is Antigenic Shift?
Involves “mixing” of genes from influenza viruses from different species
When does an “Epidemic” occur?
When there are significantly more cases of the same disease than past experience would have predicted
What is Epidemiology?
To study the cause (or etiology) of disease(s), or conditions, disorders, disabilities, etc
Structure of Covid-19/SARS-CoV-2
• Spike Protein
• Envelope Proteins
• Membrane Glycoproteins
• Nucleocapsid Protein
• RNA
Common Symptoms of Covid-19/SARS-CoV-2
• Mild to moderate flu-like symptoms
• Fever
• Cough
• Diarrhoea
• Shortness of Breath
Rare complications of Covid-19/SARS-CoV-2
• Respiratory Failure
• Systemic Inflammation
• Can lead to further consequences including Multi-Organ Damage
Role of Spike Protein
Plays a key role in viral pathogenesis, evolutions, and transmission
S protein subunits and their variable conformational states significantly affect the virus pathogenesis, infectivity, and evolutionary mutation
Mechanism of Entry of Covid-19 (7)
1) CoV binds to ACE2 cell receptors of epithelial cells in respiratory tract, via
Spike Protein
2) Binding of CoV receptor mediates proteolytic cleavage and fusion with host
cell membrane
3) Viral RNA released into host cell cytoplasm, viral nucleoproteins uncoat
4) Viral RNA translated to produce unglycosylated proteins
5) Proteins trafficked through Golgi, where they are glycosylated
6) Viral capsids assemble from viral RNA and N-Proteins in cytoplasm
7) Vesicles fuse with cell membrane and release CoV virions into lumen
